Multiple deflection cathode-ray tube



Nov, 29, 1949 P. J. sr-:LGIN

MULTIPLE DEFLECTION CATHODE-RAY TUBE Filed Feb. 1

Noi

INVENTOR PAUL J. SELGIN ATTORNEY Patented Nov. 29, 1949 UNITED STATES PATENT O F F I CE MULTIPLE DEFLECTION CATHODE-RAY TUBE Application February 1, 1947, Serial No. 725,828

12 Claims.

This invention relates to cathode ray tubes and particularly to that type of tube wherein an electron beam is deflected under the control of a signal over a target electrode structure whereby to effect signal modulation and/or amplification.

There are numerous cases where a cathode ray tube of the so-called deection type may be used to a greater advantage than a conventional grid-controlled vacuum tube. In general, it is possible to achieve a higher ratio oi mutual conductance to average input current in a cathode ray tube than in a grid-controlled vacuum tube, particularly at low signal levels. Likewise, by suitable electrode design, a cathode ray tube of the deflection type may be used to produce a greater linearity of response. Additionally, amplication of the deilected electron beam may be conventionally secured by the employment of an electron multiplier mounted in the same envelope with the cathode ray tube.

However, it is not always possible to secure the desired sensitivity when using a cathode ray tube as a signal amplier, for example. In order to minimize signal distortion, it is necessary in many cases to develop an electron beam which has a relatively small cross-section. To produce such a beam and yet to maintain a relatively high order of electron concentration in the beam, it is necessary to produce a relatively high acceleration of the electrons. In this manner there is produced what is known as a stiff beam which is relatively diiiicult to deflect. Such a characteristic, however, is not advantageous when sufficient deiiecting energy is available. But, where it is desired to utilize signal energy with a minimum of preamplication as the source of deflecting voltage, only a relatively small deflection of the electron beam is produced. It, therefore, is difcult to avoid introducing some distortion in the signal derived from the output circuit ci the device when small beam deflections only are available.

It is an object of the present invention, therefore, to provide a cathode ray tube of deection type which is capable of achieving a substantial deflection of the electron beam under the control of relatively small deflecting voltages.

Another object of the invention is to provide a cathode ray tube of the deflection type having an electrode structure and arrangement capable of producing a multiple deflection of an electron beam under the control of relatively small deflecting voltages, whereby to produce at least one beam deflection of substantial magnitude.

Still another object of the invention is to provide a novel method of signaling, utilizing a multiple deflection of an electron beam.

In accordance with this invention, there is provided a cathode ray tube having means for developingV anielectron beam.' The tube alson is provided with a plurality of beam deflecting systems and a plurality of target electrode systems. The deecting systems and the target electrode systems are arranged alternately along the path of the beam. By means oi the rst one of the deiecting systems the beam is deected over a succeeding target electrode system. A succeeding deiiecting system is coupled to a target electrode system which precedes it, in order to eiect another deflection of the beam.

The first target electrode system is constructed in such a manner that it is capable of inter-- cepting only a portion of the electron beam. The unintercepted portion of the beam is deflected by means of a succeeding deecting system over another target electrode system.

More speciiically any one or all of the target electrode systems may include an electron multiplier. In such a case the electrode structure, which is impinged by the deflected beam, is a good emitter of secondary electrons. In cases where the first target electrode system includes an electron multiplier, the second deiiecting system may be energized by coupling either to the secondary electron emissve electrodes, or to the electron collecting electrodes of the first target electrode system. In a preferred form of the invention all deecting systems are energized in phase, so that the beam is deected in the same direction by all defiecting systems. Accordingly, if the coupling of the second deilecting system is made to the electron collecting electrodes of the rst target electrode system, the coupling of the respective deecting electrodes must be made to the collecting electrodes which are located on the opposite sides of the beam path.

In accordance with the novel method of the present invention, a multiple deflection of an electron beam is effected. The initial deflection is efiected under the control of a signal. Additional beam deflection is eiiected under the control of preceding deiiections.

For a better understanding of the invention, together with other and further objects thereof, reference is made to the following description., taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

In the drawing, Fig. l is a diagrammatic illustration of a cathode ray tube embodying one form ef the invention, together with suicient circuit details to demonstrate one mode of operation of such a device; and

Fig. 2 is a fragmentary illustration of a detail of the rst target electrode structure.

Having reference now to Fig. l of the drawing, the cathode ray tube is provided with an evacuated envelope I I. An electron gun I2, shown diagrammatically, is mounted in one end of the tube envelope. The electron gun may be entirely conventional and develops an electron beam I3 which is projected toward the other end of the tube in which is located the target electrode structures. A pair of deflecting plates I4 is located adjacent the path of the beam. Also, there is provided a first target electrode structure located generally in the path of the beam and consisting of a pair of plate electrodes I5 mounted at an angle relative to the path of the beam. The plates I5 may be separate structures as shown, or if desired may be formed in a unitary structure. As illustrated herein, the two plates I5 are separated from one another, leaving an aperture in the path of the undeflected electron beam. Obviously, if the plates I5 are part of the unitary structure a similar suitable aperture may be provided. In the present case the plates I5 serve as dynode electrodes; that is, they are capable of emitting secondary electrons when impacted by a primary electron beam. Adjacent to the dynodes I5 is located a pair of electron collecting plates i5.

Farther along the path of the electron beam there is mounted a second deflecting system comprising a pair of parallel plates Il. Finally, there is provided a second target electrode structure consisting of a pair of dynodes I8 and a pair of electron collectors I9. In the illustrative embodiment oi the invention, both target electrode systems are shown as similar structures, except that the second system need not be provided with the aperture required in the rst system.

Such a cathode ray tube may be used in cooperation with a source of signals 2| for amplifying these signals and impressing them upon a utilization circuit 22. The signal source 2I is connected to an input resistor 23, the terminals of which are coupled to the plates I4 of the rst deiiecting system. The amplied signal eiects are developed in an output resistor 24, the terminals of which are coupled to the electron collectors I9 and also to the utilization circuit 22.

The tube electrodes and auxiliary circuits are energized for operation by suitable connections, to be described, to a power source such as represented by a battery 25. The battery voltage is distributed to the tube electrodes and auxiliary circuits by a voltage divider 26 which is co-nnected to the terminals of the battery. The grounded negative terminal of the power supply is connected to the source of electron emission forming a part of the electron gun I2 in a conventional manner. A somewhat more positive potential is impressed upon the rst and second target electrode plates I5 and I8, respectively. The positive terminal of the power supply is connected to a center tap on both the input and output resistors 23 and 2li, respectively. It also is connected to a center tap on a resistor 21, the terminals of which are connected to the collector electrodes It of the rst target electrode structure. Finally, the plates I 'I of the second delecting system are coupled suitably to the collector electrodes IS of the rst target electrode system. As shown, the upper delecting plate II is connected to the lower collector plate I6. Similarly, the lower deflecting plate is connected to the upper collector.

Before describing in detail the operation of the described device, a brief reference will be made to Fig. 2. This view is one in elevation of the rst target electrode dynodes I5. The inner '4 edges of these two electrodes are serrated generally in the manner shown to form a series of spaced projections or teeth 28. Preferably the width of the teeth is maintained relatively small and the spacing between the teeth relatively large. The teeth are formed so that they will be deeper than the maximum deflection of the electron beam. By means of such a structure, the greatest portion of the electron beam, whether or not it is deflected, is not intercepted by the plates I5. However, a small percentage of the electron beam will be intercepted by the teeth 28, depending upon the magnitude of the beam deflection.

Referring now to the operation of the device, in accordance with the present invention, it will be assumed that a signal of suitable polarity is impressed upon the input resistor 23 to develop voltages at the iirst deecting plates I4 of a character whereby to eiiect an upward deflection of the beam I3. As previously described, the major portion of this beam passes without interruption through the aperture formed by the toothed dynode plates I 5. This portion of the electron beam will be considered subsequently. By reason of the upward deflection of the beam there is intercepted by the teeth 28 of the upper dynode I 5 a greater number of electrons than are intercepted by the teeth of the lower dynode I5. Consequently, a greater number of secondary electrons will be liberated from the upper plate than from the lower plate, and it follows that more electrons will be nally collected by the upper collector it than by the lower collector IG. Therefore, there is developed a voltage in the resistor 2l which is representative of the amount by which the beam is deflected. The potential of the lower collector is more positive than the upper collector and, since these two electrodes are cross-coupled to the second deflecting plates Il, this deflecting system also produces an upward deflection of the larger portion of the beam which is not intercepted by the rst target electrode structure. A sulcient number of electron multiplying stages may be provided in the rst target electrode structure to impress voltages of considerable magnitude upon the second deecting system. By this means, then, a much greater deflection of the electron beam may be produced so that signal eiects varying over a considerable range will be developed in the output circuit resistor 24. The beam deflection over the dynodes I8 is substantially similar to that described in connection with the dynodes I5.

It should be evident that, by amplifying the electron beam in the first target electrode structure where relatively small deiiecticns are produced under the control of the signals, voltages of considerably increased magnitudes may be developed as representative of the signals for controlling the larger deflection of the beam by the second deilecting system. Thus, there is provided a device which has the desirable attributes of good linearity of response and a favorable ratio of mutual conductance to average input current and, at the same time, is capable of being energized by the signals having a minimum of preampliiication.

It is to be understood that, while the invention is disclosed herein as having two deflecting systems and two target electrode systems, it is not necessarily so limited. *.Obviously, more than two beam deflections may be effected by providing additional deiiecting systems and target electrode systems. The additional deflecting systems may be coupled to a preceding target electrode system in accordance with the present disclosure.

While there has been described what at present is considered the preferred embodiment of the invention, it will be obvious to those skilled in the art that various changes and modications may be made therein without departing from the invention, and it, therefore, is aimed in the appended claims to cover all such changes and modilcations as fall within the true spirit and scope of the invention.

What is claimed is:

1. A cathode ray tube comprising, means for developing an electron beam, a plurality of beam deflecting systems, a plurality of target electrode systems, said denecting systems and said target electrode systems being arranged alternately along the path of said beam, means including the iirst one of said deecting systems for delecting said beam over a succeeding target electrode system, and means coupling one of said succeeding deecting systems to a preceding target electrode system for effecting another deflection of said beam.

2. A cathode ray tube comprising, means for developing an electron beam, a series arrangement along the path of said beam of a rst deflecting system, a first target electrode system, a second deflecting system and a second target electrode system, said nrst target electrode system being constructed to intercept only a portion of said beam, and means coupling vsaid second deflecting system to said first target electrode system for energizing said second deecting system.

3. A cathode ray tube comprising, means for 5 a second target electrode system, said rst target electrode system having an aperture located in the undeflected path of said beam, whereby to permit passage of the major portion of said beam, and means coupling said second delecting electrode system to said first target electrode system for energizing said second deilecting electrode system in phase with said first deflecting elec trode system.

4. A cathode ray tube comprising, means for developing an electron beam, first means located adjacent to the path of said beam for effecting a rst deflection of said beam, a pair of sampling target electrodes located behind said rst deflecting means to intercept only a portion of said denected beam, second means located behind and coupled to said sampling electrodes for eiecting a deection of the unintercepted portion of said beam, and a main pair of target electrodes located behind said deflecting means for respective impingement by said unintercepted beam.

5. A cathode ray tube comprising, means for developing an electron beam, means located adjacent to the path of said beam for eiecting a first deection of said beam, a pair of sampling target electrodes located behind said first deilecting means and each having such a configuration as to intercept only a portion of said deflected beam, a pair of dellecting electrodes 1ocated behind and coupled to said sampling electrodes for eiecting a deection of the unintercepted portion of said beam, and a main pair of target electrodes located behind said pair of deecting electrodes for respective impingement by said unintercepted beam in proportion to the deection thereof.

6. A cathode ray tube comprising, means for developing an electron beam, a nrst pair of deilecting electrodes located adjacent to the path of said beam for effecting a first deflection of said beam, a pair of sampling target electrodes lccated behind said first pair of deecting electrodes and each having an uneven edge conguration, whereby to intercept only a portion of deflected beam, a second pair of deecting electrodes located behind said sampling electrodes and each being coupled to one of said pair of sampling electrodes lor effecting a second deflection of the unintercepted portion of said beam, and a main pair of target electrodes located behind said second pair of deflecting electrodes for respective impingement by said unintercepted beam in proportion to said second beam dencetion.

7. A cathode ray tube comprising, means for developing an electron beam, a rst pair of deflecting electrodes located adjacent to the path of said beam for effecting a first beam deflection, a pair of sampling secondary electron emissive target electrodes locate-d behind said rst pair of delecting electrodes and each having an uneven edge conguration, whereby t0 intercept a relatively small portion of said deliected beam, a pair of electron collecting electrodes located adjacent to said sampling electrodes, whereby to collect respectively secondary electrons in proportion to said rst beam deflections, a second pair of deflecting electrodes located behind said sampling electrodes and each .being coupled to one of said pair of collecting electrodes for effecting a second dellection of the unintercepted portion of said beam, and a main pair of target electrodes located behind said second pair of deflecting electrodes for respective impingement by said unintercepted beam in proportion to said second beam deilection.

8. A cathode ray tube comprising, means for developing an electron beam, a first pair of dellecting electrodes located adjacent to the path of said beam for effecting relatively small deflections of said beam, a pair of sampling target electrodes located behind said first pair of deflecting electrodes an-d having notched edges, whereby to intercept a relatively small portion of said deflected beam, a second pair of deflectingr electrodes located behind said sampling electrodes and each being coupled to one of said -pair of sampling electrodes for effecting relatively large deflections of the unintercepted portion of sai-d beam corresponding to said relatively small deflections, la main pair of secondary electron emissive target electrodes located behind said second pair of deilecting electrodes lfor respective impingement by said unintercepted beam in proportion to said relatively large deections, and a pair of electron collecting electrodes located adjacent to said main target electrodes, whereby to collect secondary electrons in proportion to said relatively large deflections of said unintercepted beam.

9. A cathode ray tube comprising, means for developing an electron beam, a rst pair of deflecting electrodes located adjacent to the path of said beam and having potentials varying according to signals for effecting corresponding relatively small deflections of said beam, a pair of sampling secondary electron emissive .target electrodes located symmetrically adjacent to the undeeoted path of said beam and provided with serrated edges, whereby to intercept a relatively small portion of said deflected beam, a rst pair of electron collecting electrodes located adjacent to said sampling electrodes, whereby to collect respectively secondary electrons in -proportion to said relatively small deflections of said beam, la second pair of defiecting electrodes located adjacent to the path of the unintercepted portion of said beam behind said sampling electrodes and each being coupled to one of said first pair `of collecting electrodes for effecting relatively large deflections of said unintercepted beam corresponding to said relatively small deflections, #a main pair of secondary electron emissive target electrodes located behind said second pair of deecting electrodes for respective impingement :by said unintercepted beam in proportion to said relatively large deflections, and a second pair 4of electron collecting electrodes located adjacent to said main target electrodes, whereby to collect secondary electrons in pro-portion to said relatively large deflections of said unintercepted beam.

l0. A cathode ray tube comprising, means for developing an electron beam, a first pair of defiecting electrodes located on opposite sides of said beam and having potentials varying according to signals for effecting corresponding relatively small deflections of said beam, a pair of sampling secondary electron emissive target electrodes located on opposite sides of the undeected path of said beam and provided with serrated inner edges, whereby to intercept a relatively small portion of said deflected beam, a first pair of electron collecting electrodes located respectively adjacent to said sampling electrodes, whereby to collect respectively secondary electrons in proportion to said relatively small deections of said beam, a second pair of defiecting electrodes located on opposite sides of the unintercepted portion of said beam behind said sampling electrodes and each being connected to one of said first pair of collecting electrodes for effectn ing relatively large deflections of said unintercepted beam corresponding to said relatively small deflections, a main pair of secondary electron emissive target electrodes located adjacent to the undeflected path of said unintercepted beam for respective impingement by said unintercepted beam in proportion to said relatively large deflections, and a second pair of electron collecting electrodes located respectively adjacent to said main target electrodes, whereby to collect secondary electrons in proportion to said relatively large deflections of said unintercepted beam.

1l. A cathode ray tube comprising, means for developing an electron beam, a first pair of .deilecting electrodes located on opposite sides of said beam adjacent to said beam developing means and having potentials varying according to signals for effecting corresponding relatively small deections of said beam, a pair of sampling secondary electron emissive target electrodes located symmetrically on opposite sides of the undeflected path of said beam and provided with serrated centrally disposed edges, whereby to intercept a relatively small portion of said deflected beam, a first pair of electron collecting electrodes located respectively adjacent to said sampling electrodes, whereby to collect respectively secondary electrons in proportion to said relatively small deilections of said beam, a second pair of defiecting electrodes located on opposite sides of the unintercepted portion of said beam behind said sampling electrodes and each being connected to the one of said rst pair of collecting electrodes located on the opposite side of said beam for effecting relatively large deflections of said unintercepted beam corresponding to said relatively small deections, a main pair of secondary electron emissive target electrodes located symmetrically adjacent to the undeilected path of said unintercepted beam for respective impingement by said unintercepted beam in proportion to said relatively large deflections, and a second pair of electron collecting electrodes located respectively adjacent to said main target electrodes, whereby to collect secondary electrons in proportion to said relatively large deflections of said unintercepted beam.

12. A signaling system comprising, a source of signals, a utilization circuit, a cathode ray tube including means for developing an electron beam, a plurality of defiecting electrodes, a plurality of target electrodes, said defiecting and target electrodes being arranged alternately along the path of said beam, means for coupling a first pair of defiecting electrodes to said signal source for effecting an initial deflection of said beam over a succeeding target electrode, means for developing at said target electrodes voltages representative of the beam deflections over said target electrodes, means for coupling succeeding defiecting electrodes to preceding target electrodes in proper polarity for effecting other deflections of said electron beam corresponding in sense to said initial deflection, and means for impressing upon said utilization circuit the voltage developed at the nal target electrode.

PAUL J. SELGIN.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,305,617 Hansell Dec. 22, 1942 2,357,922 Ziebolz et al Sept. 12, 1944 

